MXPA01002767A - GLASS FIBERS WITH IMPROVED DURABILITY VIA LOW MgO AND Al2 - Google Patents

Abstract

The glass compositions of the present invention contain a limited amount of Al2O3 and MgO resulting in a glass fiber having an acceptable chemical durability for product performance while providing a relatively high biosolubility. The composition includes an amount of BaO which improves fiber durability while controlling viscosity and other processing parameters. The compositions further include amounts of Na2O, K2O, and CaO, which have the effect of increasing fiber biosolubility and allows for the use of reduced amounts of Al2O3 and MgO in the composition. The glass compositions of the present invention have KI values that generally equal or exceed a KI value of 40 and are suitable for rotary processing. The compositions have liquidus temperatures below about 1600°F, and have a&Dgr;T (T at 1000 Poise-liquidus T) of at least 130°F.

Description

GLASS FIBERS WITH IMPROVED DURABILITY VIA MgO AND AL2Q3 BAJOS BACKGROUND OF THE INVENTION The present invention is directed generally to glass compositions, and more particularly to glass fiber compositions having high Kl values and durability. The fiberglass or vitrofibre insulation is well known and has been a commercial product for many years. Fiberglass insulation is widely used both residentially and commercially. Generally, the insulation is made of interwoven lime soda and lime alumina borosilicate glass fibers, which are held together with an adhesive or binder. Glass fibers are generally produced using SiO with a number of additives, such as Na20, K20, CaO, MgO, BaO, B203 and Al203, which improve the different properties of the fibers. The adhesive or binder can be any suitable material, but in a manner. Most common is a phenol formaldehyde resin or formaldehyde urea resin. A rotating process is often used to form glass fibers. The rotary process typically involves the introduction of molten glass into a rotating device, called a spinner, which contains a plurality of holes circumferentially distributed around the spinner. The spinner rotates around an axis to produce a centrifugal force on the molten glass. The rotation of the spinner forces the glass through the plurality of holes. An annular flow of hot gases is passed around the spinner to contact and attenuate the fibers passing through the holes. A spray nozzle is placed to coat the attenuated fibers with the adhesive or binder. A conveyor machine collects the coated fibers with adhesive or binder in the form of an endless cloth, or block of fibrous material, and the endless cloth is heat cured to produce the final insulation. The rotating process can be used to produce the insulation having different densities by varying the speed of the conveyor and the thickness of the cured insulation. Fiberglass insulation has been used to replace, or instead, the isolation of asbestos fiber in many applications. It is generally believed that asbestos fibers, when inhaled, can result in significant diseases in man. Although the exact mechanism responsible for the biological activity of asbestos fibers is unknown, it is widely believed that an important factor in the mechanism is the residence time of the fibers in the lungs. Unlike asbestos, glass fibers have not been linked to diseases in man. Fiberglass also seems to have a much shorter residence time in the lungs than asbestos fibers. The residence time of the glass fibers in the lungs will depend, at least in part, on the chemical dissolution of the fiber. The rate of chemical dissolution of a material in biological fluids is generally known as the biosolubility or biological degradability of the material. Despite the absence of the link between glass fibers and human diseases, some countries, for example Germany, have proposed regulations on the use of glass fibers in insulating products. Fiberglass compositions that meet the standard in the proposed regulations are considered those that are free of suspicion as disease causing agents and can be used for both commercial and residential facilities. The regulations are based on the desire to minimize the residence time of a fiberglass in the lungs. It is expected that the minimization of fiberglass residence time will decrease the possibility, if any, of subsequent diseases. The proposed German regulations for biosolubility require that glass fibers have a numerical index (Kl) greater than or equal to 40 to be considered free of suspicion. The Kl index, sometimes referred to as the Wardenbach index, is described by the equation: KI = S (Na20, K20, CaO, MgO, BaO, B203) -2 (A1203) Where the value of each oxide corresponds to the percentage by weight of that oxide in the composition of the glass. The index used in the regulation places severe restrictions on the glass compositions, specifically on the levels of alumina (A1203) and implicitly on the levels of silica (Si02) in the glass composition. Manufacturers must now produce glass fibers that meet the proposed regulations, while maintaining standard performance criteria or performance for the products. The criteria include that fiberglass can be produced using standard wool processes to have sufficient durability in use, and acceptable insulating properties. Silica is the main component in fiberglass and provides most of the structural and physical properties of fiber. Alumina is mainly used in fiber to provide additional durability to the fiber. Initial attempts to produce fiberglass that comply with the regulations involved using reduced levels of alumina in the glass composition to increase the Kl index. However, low alumina glass fibers tend to have poor durability. A number of glass compositions have been reported as having improved biosolubility or biodegradability. For example Potter, U.S. Patent No. 5,055,428, Cohen et al., U.S. Patent No. 5,108,957, Nyseen, U.S. Patent No. 5,332,698, Bauer et al., U.S. Patent No. 5,401,693, and Mattson et al., U.S. Patent Nos. 5,523,264 and 5,523,265 (which are hereby expressly incorporated by reference), all describe fibers having improved biosolubility.

Also, published PCT applications WO 97/49643, WO 95/31411, WO 95/32925, WO 95/32926, WO 95/32927 and WO 95/35265 and numerous published German applications such as DE 19631782A1 have reported glass compositions having greater degradability. Glass compositions that conform to Kl index regulations generally provide higher levels of B203 to partially offset the increased levels of alumina. However, a disadvantage of including increased levels of B203 are the higher costs associated with B203. Another disadvantage is that B203 is volatile and higher concentrations produce higher gas emissions that must be controlled, which can also lead to an increase in costs. For these reasons, it is preferred to limit the content of B203 to less than 15%. The use of high levels of MgO in glass compositions conforming to the regulations of the Kl index decreases the A120 content but with a resulting decrease in fiber durability. Despite the improvements presented in the patents and applications mentioned above, the glasses do not satisfy the Kl > 40 standard or significant processing and performance or performance problems continue to exist. The decrease in performance or performance and the increase in processing costs for glass compositions designed to meet the new biological standards is a clear disadvantage in the industry. In addition, compositions with higher alumina content of the prior art provide performance versatility or performance, although they are not acceptable in the emerging regulated market or suffer from higher processing costs. The use of MgO instead of A1203 increases the Kl index of the fiber composition but with a decrease in the durability of the fiber. Accordingly, there is a need for a glass composition having higher biosolubilities (Kl value> 40), and at the same time possessing acceptable processing properties, such as viscosity and temperatures in the liquid state, as well as performance or performance and durability. acceptable in use.

BRIEF DESCRIPTION OF THE INVENTION The above objectives and others are achieved by glass fibers having compositions according to the present invention. The glass fibers contain a limited amount of A1203 and MgO which results in fibers that have an acceptable chemical durability for the performance or performance of the product and at the same time provide a relatively high biosolubility. The composition includes an amount of BaO, which improves the durability of the fiber and controls both the viscosity and other processing parameters. The compositions further include amounts of Na203, K20, CaO, which have an effect on the increase of the biosolubility of the fiber and allow the use of reduced amounts of A1203 and MgO in the composition. The glass compositions have Kl values which are generally equal to or exceeding a Kl value of 40 and are suitable for rotary processing. The compositions have liquid state temperatures less than about 1600 ° F (871.1 ° C), and have a? T (T to 1000 Poises-T in liquid state) of at least 130 ° F (54.4 ° C). In one aspect of the invention, BaO is replaced by B203 to improve durability at alumina levels approaching 1%. In one aspect of the invention, the total amounts of Fe203, Ti02 and Zr02 are limited. Preferably the total amounts of iron, titanium and zirconium oxides are limited to less than 1% (for clarity, all percentages are in weight percent unless otherwise noted). A fiberglass composition having 49-59 weight percent SiO2; 0.9-2 weight percent A1203; 0-3 weight percent MgO; 2-13 weight percent BaO; 5-12 percent CaO; 0-22 weight percent K20 and Na20; 0-22 weight percent of B203, as well as small amounts of other oxides provide a durable, biosoluble fiber, which satisfies the equation: (BaO + B203 + Na20 + K20 + MgO + CaO) -2 * A1203 > The compositions of the present invention improve fiber compositions that meet the proposed biosolubility standards, while maintaining acceptable performance or performance and durability such as fiberglass insulation. Accordingly, the present invention overcomes the aforementioned difficulties of the prior art by satisfying public health standards and commercial requirements. Those advantages and others will become apparent from the following detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described generally with reference to the preferred embodiments of the invention so far, solely for the purpose of providing examples of the invention and not for the purpose of limiting the same. Applicants have found that glass processing and biosolubility and fiber durability acceptable in the glass fiber can be maintained by providing compositions that include alumina in a range of 0.9-2%, magnesia in the range of 0-3%, B203 in the range of 2-13%, and increased levels of alkali and alkaline earth oxides over the prior art. The compositions of the present invention provide a balance between durability and increased bioavailability to overcome the disadvantages of the prior art. The content of Si02 in the compositions of the present invention ranges from 50-57%.

The content of A1203 in the composition should be less than about 2% to provide durability with sufficient performance or performance without substantial deterioration of fiber biosolubility. It is preferred that the alumina content of the composition fluctuate from 0.9-2% to control biosolubility. To achieve the desired Kl values, it is desirable to reduce the amount of alumina, which allows an increase in the amount of silica, as well as a reduction in the amount of modifiers such as BaO, CaO, Na20, B203 and K20 needed. The decrease in alumina levels decreases the durability of the fibers, however, it has been discovered that the reduction of MgO levels with the decrease in alumina levels increases the durability of the fiber. Especially, of the modifiers, CaO substantially increases the durability of the fibers. However, the increase in CaO levels increases the temperature in the liquid state and also decreases the viscosity of the glass, which results in difficulties in the formation of the fibers during spinning. The increase in MgO amounts improves the Kl index, however, the increase in MgO levels reduces the durability of the resulting fibers.

Na20 is included in a fluctuating amount of approximately 12-20% depending on the desired properties. Na20 will generally provide lower viscosities and better melting characteristics for glass. K20 is typically an impurity which is included in alumina. K20 is typically less than 2%, depending on the amount and purity of the alumina included in the composition. The K20 at low levels tends to improve the characteristics associated with the Na20. The MgO is included in the composition at 0-3% intervals to provide lower liquid temperatures and viscosities at a lower cost. Preferably, the MgO levels are in the range of 0-2%. When the MgO is included in amounts less than about 3%, the resulting glass fibers have better durability with respect to water. In CaO it is included in the composition in quantities that fluctuate from 5-12%. The CaO provides a lower viscosity and better durability. The BaO is included in an amount of 2% -13%. He BaO is added to compensate for the lower amount of MgO. The use of BaO provides greater durability on the fibers, including greater amounts of MgO, without the decrease in viscosity caused by the inclusion of CaO. It has been found that the use of BaO increases the durability and controls the processing parameters such as viscosity, and maintains the desired Kl index. B203 is included in the composition in amounts ranging from 0-22%. The B20 serves mainly to significantly lower the temperature in the liquid state and the viscosity of the composition. In view of the disadvantages associated with the different constituents included in the glass compositions, the present invention aims to balance the composition and decrease both the amount of A1203 and MgO to provide a more versatile glass and which functions better and maintain at the same time a suitable biosolubility. The following examples are provided to demonstrate the present invention and not to limit it.

EXAMPLES A number of compositions were prepared by methods known in the art to provide examples of compositions of the present invention. For each sample, the temperature in the liquid state of the composition was determined. Also, the temperature at which the viscosity of the glass is about 1000 poise (Tlog3 viscosity) was determined. The T, the difference between the viscosity Tlog3 and the temperature in liquid state, was marked as "visc-liqu'A In addition, durability tests were made preparing continuous fibers of 10 μm in diameter of each composition. The fiber was placed in 100 ml of water and kept at a temperature of 205 ° F (96.11 ° C) for 24 hours After exposure to water, the sample was removed from the water, dried and weighed. after the test it was compared with the weight before the test to calculate the% weight loss during the test As can be seen from the examples in the attached table, the compositions of the present invention provide lower levels of alumina and magnesia, while remaining within the requirements of the proposed Kl index and maintaining adequate durability and T. The theoretically acceptable compositions for the production of glass fiber by a rotating process appear to be possible with less than 2% A1203 and less than about 3% MgO. In addition, the present invention provides the decrease in the amount of A1203 and MgO used in glass compositions. The durable fibers of those compositions satisfy both of the Kl index regulations and can be processed by standard rotary methods. The examples demonstrate that the compositions within the present invention can be employed in various amounts to design specific properties of the compositions. Example 7 shows that the effect of MgO can be crushed by high concentrations of B203. Example 3 shows the harmful effect of including more than 3% MgO. Examples 24-27 show the damaging effects of a high content of iron, titanium and zirconium oxide as compared to Example 23, which is the base case. Those skilled in the art will appreciate that a number of modifications and variations can be made to the specific compositions of the present invention without departing from the scope of the present invention. It is intended that such modifications and variations be covered by the above specification and the following claims.

Claims (17)

1. A fiberglass formed of a composition, characterized in that it comprises: 49-59 weight percent SiO2; 0.9-2 weight percent A120; 0-3 weight percent MgO; 1-13 weight percent BaO; 5-12 percent CaO; 0-22 weight percent K20 and Na20; 0-22 weight percent of B03, where the fiberglass has a fiber weight loss of less than 4% after exposure to water at 205 ° F (96.1 ° C) for 24 hours and a? T of at least 130 ° F (54.4 ° C).

2. The fiberglass according to claim 1, characterized in that the composition satisfies the equation: (BaO + B203 + Na20 + K20 + MgO + CaO) -2 (A1203) > 3.

The fiberglass according to claim 1, characterized in that the content of B203 ranges from 0-15 weight percent. .

The fiberglass according to claim 1, characterized in that the ingredients include, in percent by weight: Si02 50-57; A1203 0.9-2; BaO 2-12; B203 6-15; Na20 13-20; K20 0-2; MgO 0-2; and CaO 5-12.

5. The composition according to claim 1, characterized in that the composition has a temperature in the ld state < of 1600 ° F (871.1 ° C).

6. The composition according to claim 1, characterized in that the ingredients include approximately, in percent by weight: SiO2 54; A1203 1.9; BaO 2.1; B203 11; Na20 19; K20 .45; MgO 1.8; and CaO 8.2. with the rest being oxides of iron, zirconium, titanium and sulfur, as well as unavoidable impurities.

7. A fiberglass insulating product, characterized in that it contains fibers comprising: 49-59 weight percent SiO2; 0.9-2 weight percent A1203; 0-3 weight percent MgO; 1-13 weight percent BaO; 5-12 percent CaO; 0-22 weight percent K20 and Na20; 0-22 weight percent B20, where the fiberglass has a fiber weight loss of less than 4% after exposure to water at 205 ° F (96.1 ° C) for 24 hours and a? T of at least 130 ° F (54.4 ° C).

8. The fiberglass insulating product according to claim 7, characterized in that the composition satisfies the equation: (BaO + B203 + Na20 + K20 + MgO + CaO) -2 (Al203) >

9. The fiberglass insulating product according to claim 7, characterized in that the content of B203 ranges from 0-15 weight percent.

10. The fiberglass insulating product according to claim 7, characterized in that the ingredients include, in percent by weight: Si02 50-57; A1203 0.9-2; BaO 1-12; B203 6-15; Na20 13-20; K20 0-2; MgO 0-2; and CaO 5-12.

11. The fiberglass insulating product according to claim 7, characterized in that the composition has a temperature in the ld state < of 1600 ° F (871.1 ° C).

The fiberglass insulating product according to claim 7, characterized in that the ingredients include approximately, in percent by weight: SiO2 54; A1203 1.9; BaO 2.1; B203 11; Na20 19; K20 5; MgO 1.8; and CaO 8.2. with the rest being oxides of iron, zirconium, titanium and sulfur, as well as unavoidable impurities.

13. The fiberglass insulating product according to claim 7, characterized in that it further comprises an adhesive or binder for retaining the fibers in a predetermined manner.

A method for preparing glass fiber, characterized in that it comprises the steps of: providing a glass melt, having a composition comprising, in weight percent: 49-59 weight percent SiO 2; 0.9-2 weight percent AI2O3; 0-3 weight percent MgO; 1-13 weight percent BaO; 5-12 percent CaO; 0-22 weight percent K20 and Na20; 0-22 weight percent B203, where fiberglass has a fiber weight loss of less than 4% after exposure to water at 205 ° F (96.1 ° C) for 24 hours and a? T of at least 130 ° F (54.4 ° C); and spinning the glass melt to form a plurality of fibers.

15. The method according to claim 14, characterized in that the composition satisfies the equation: (BaO + B203 + Na20 + K20 + MgO + CaO) -2 (A1203) >

16. The method according to claim 14, characterized in that the content of B203 ranges from 0-15 or hundred by weight.

17. The method according to claim 14, characterized in that the ingredients include, in percent by weight: Si02 50-57; A1203 0.9-2; BaO 2-12; B203 6-15; Na20 13-20; K20 0-2; MgO 0-2; and CaO 5-12. 19. The method according to claim 14, characterized in that the composition has a temperature in the liquid state < of 1600 ° F (871.1 ° C). 20. The method of compliance with the claim 14, characterized in that the ingredients include approximately, in weight percent: SiO2 54; A1203 1.9; BaO 2.1; B203 11; Na20 19; K20 5; MgO 1.8; and CaO 8.2. with the rest being oxides of iron, zirconium, titanium and sulfur, as well as unavoidable impurities.